Centrifugal pump



Oct. I7, A1944. M. H. ARvEsoN 2,360,464 I CENTRIFUGAL PUMP- Filed July 25, 1942 j. WA4 www@ `from a lower pressure Patented Oct. 17, 1944- UNIATYED STATE 2,360,464 CENTRIFUGAL PUMP Maurice H. Arveson, Flossmcor, Ill., assignor to Standard Oil Company,

ration of Indiana Chicago, Ill., a corpo- App'lcation July 25, i942, Serial No. 452,274

7 Claims.

The present invention relates to centrifugal pumps for riely divided solid material such as abrasive powders and the like. This invention is particularly useful for handling powdered catalysts in apparatus for catalytically treating petroleum products. i

Many difculties, particularly erosion and caking, arise in devices for impelling powdered solids. Whenever a powdered abrasive solid comes between moving metal surfaces erosion occurs and the impelling device wears out quickly. In other devices where the powder is permitted to come to rest, caking or bridging occurs and the device becomes inoperative. The present invention provides a method and means for impelling or pumping a finely divided solid material, particularly zone to a higher pressure zone. -By the term "finely divided solid material I mean to include those materials which have a particle size of from about 50 mesh to about 500 mesh and which arenormally subject to packing or caking and which cause erosion.

Powdered catalyst systems have been 'found to be far superior t'o fixed bed systemsvin many respects, but a serious problem in powdered catalyst systems is that of handling the abrasive powder and particularly introducing this powder from a zone of low pressure to a zone of high pressure. Ordinary pumps or blowers cannot be used for this purpose because when powdered catalyst comes into contact with metal surfaces which are subject to sliding friction, the metal surfaces quickly become eroded and'worn away by the abrasive action of the catalyst. 'A pressure screw of gradually diminished pitch has been proposed as a solution to this problem but the friction losses in such a screw are enormous, and here again the erosion due to contact of the catalyst particles with moving metal surfaces makes it necessary to replace metal partsat very short intervals. Pumps of the pressure-screw type are Cl. SO2-36) pump for transferring powdered catalyst material from a lower pressure zone to a higher pressure zone without excessive wear of the pump andA without disintegrating or agglomerating the catas lyst material.

Figure 1 is a vertical also subject` to the disadvantage that they arey `ent and cause anagglomeration of the catalystHwhich seriously impairs itsA acti 'ty.

An object of the present invention isto provide a .means for handling powdered catalyst which will avoid the above diiculties.

A further object, is to provide a pump which is subject to less erosion than in previously known devices.

Still another objectis -to provide a pump for a finely divided solid material wherein bridging or caking of the material is prevented. c'

A still further 'object is to provide animp mechanically very vinefiici oved Other objects of the invention will be apparent as the description thereof proceeds. With the foregoing objects in mind, the present invention provides for a centrifugal impeller which receives the finely divided solid material from a low pressure zone and forces it by centrifugal action into a high'pressure zone. In order to prevent the powdered material from caking and bridging in the impeller, I have provided means for keeping the material aerated while it is passing through the impeller.

One form of the invention will be described in detail with reference to the drawing forming a part of this specification.

cross-sectional view of one example of my improved centrifugal pump;

Figure 2 is anV nlarged cross-sectional view of a portion of the pump shown in Figure 1;

Figure 3 is a plan view of another portion o! the pump drawn along lines 3-3 of Figure 1; and

Figure 4 is anenlarged cross-sectional viewof still another portion of Figure 1.

In the detailed description which follows I shall refer particularly to powdered catalyst material, although other powdered solids are within the scope of the present invention.

- Referring to the drawing, a chamber or hopper l I containing the powdered catalyst is aeratedby means of inert gas entering aeration prevents bridging and ensures steady, even and continuous flow of thepowder in a. liquid-like state down to the npeller. A rotatable neck member i3 connects the hopper il with the chamber or receiving hopper I4 which is under a higher pressure than hopper il. The neck member'l3 is provided with a pulley I5 which may be driven by a belt or by any other/ driving means, mechanically, electrically, pneumatically, or otherwise. Conventional stuffing boxes I6 and -II are used to permit rotation ofthe neckmember while at the same time preventing leakage of the aerated powder. A cleansing gas under high pressure may be introduced into the stumng boxes to prevent any powdered catalyst from entering the stuffing boxes and eroding the surfaces thereof. Cgxnnected to and preferably integral with the ,low end of neck l3is disc I8 which, as shown in the drawing, may

be slightly conical in shape.

through line I2. This 2 2,360,464 neath disc I8. A rotatable hollow shaft 2I passes of -gas in the dense phase at a high ,enough'level from the pulley I5 to which itis securedtby spider to keep the powdered catalyst in a free-flowing' 22 down through neck I3, plate 20, disc I9 and condition. .This dense phaseVwhile being centhe wall of the receiving hopper I4. Disc Isris trifuged, creates a much increased pressure near securely xed to hollow shaft 2I whileI plate 20 I the periphery of the impeller and the dense phase may be securely fixed or keyed for vertical sliding moves out against the higher pressure in the rernovement or loosely nounted thereon. Itis clear ceiving hopper I4.

that when thefneck I3 is rotated, the hollow shaft The operation of the centrifugal pump is as 2I as well as the discs I8 and 'I8 will rotate also. follows:

The powdered catalyst will pass downwardly l0 The aerate'd powdered catalyst in hopper II through the neck member I3 past the spider 22 passes down through rotating ,neck I3 into zone into the centrifugal zone 21 between disc I8 and 21. lSome motion is imparted to the catalyst by plate where it wlllbe thrown outwardly into the spider 22 as well as by contact with rotating receiving hopper I4, finally passing. therefrom disc I8 and plate 28. As the powdered material 4an upwardly and inwardly curved flange-like 20 riphery thereof and'in receiving hopper I4 while portion extending approximately to the upper the pressure in aeration gas zone 26 is from a surface of plate 20. Plate 20 has a bevelled fraction of an ounce to vseveral ounces greater outer edge which cooperates with the flange-like than the gas pressure in receiving vhopper I4. portion 25 to form an annular channel communi- Since the aerationv gas in zone`28 is directed into This construction permitsthe plate 20 to revolve i or caking. The momentum of the particles 0f freely around hollow shaft 2I and at the same 30 powdered catalyst is great enough to prevent the time move upwardly or downwardly depending particles from being blown back into zone 21 and on the pressure exerted'on the upper and lower they Will pass through the Opening between surfaces of said plate..V l curved flange 25 and flange 24 into the receiving At the lower end of hollow Vshaft 2I externally. hopper I4 which is under greater pressure than of receiving hopper l I4 is a swivel joint 30,1;0 35 hODper II. whichvis connected line 3I An inert aeration gas In order to prevent the powdered catalyst from is passed through line 3l and hollow shaft2| and backing up fromreceiving hopper I4 to hopper II through openings 32 provided in hollow shaft 2I when the impel'ler. comprising discs I8 and I 8 into aeration gas zone 26.' The aeration gas and plate 20, is stopped. conventional check valves passes from zone 26 into centrifugal zone 21 40 .34 and 35 may be inserted in the bottom of hopin` zone 21 and thereby prevents the caking or 45 valves 34 and 35 are optional since the plate will tinuous iow of the catalyst into receiving hopper when the impler is stopped due to the pressure I4. In lFigure 3 are shown aeration holes 33 exerted on the bottom of plate 28 by the aeration flow of aeration gas from zone 28 into ,centrifugal '50 spring 28 and the pressure on top of the plate- In zone 21. In addition, other aeration holes maynormal operation the plate 28 is drawn down-by be provided in plate 20 nearer the center thereof. the action. of spring28 which is sufllcient to over- A pressuring gas can be introduced into receiving come the diierence between the pressures on the hopper I4 through linel 32,. top and bottom of plate 20. When the plate 2l is kCatalyst: powder when in its fuuy compacted in its upper position the aeration gas in Zone 2l stateA or settled condition weighs 'fronl about 40 will pass through aeration holes 33 into zone 21 similar powder is fed to the pump while in an in aerated form. At the sametime a portion of aerated dense phase condition and has a density, the aeration gas in zone 28 will leak-past the of the orrier of from about 8 toabout 30 pounds 60 curved ange 25 into pressure hopper I4 thereby per cubic foot, which, in other words, is about 15 preventing any back flow from occurring. to about 50% of its density when fully compacted. f The operation of the centrifugal pump, accord- In the centrifugal zone 21 the density of the pow' ing 'to the present invention. may be controlled by about 25 to about 60% 'of the fully compacted c5 thereof. For' exainple,tl'1e rate oflow-of pow'- in a densephase condition which :night be termed I trolled by lincreasing or decreasing the flow of r liquid-like." This dense phase has the free pressuring .gas ini line 32 by means of valve 31.

vBecausetof this characteristic of compressibility shaft 2I. Likewise, a regulating valve 3 8 may be an aerating gas 'is introduced near the periphery inserted in pipe 23.A If this latter method of conofthe disc I8 and plate 20 to maintain the volume 15 trol is used, it is desirable .to combine therewith ods of control of the flow of powdered catalyst comprises regulation of flow of line 32 by means of valve 31 and speed of rotation of shaft 2l.

AIt is evident that when the plate 20 is securely mounted on the shaft 2i it may be unnecessary to have the aeration holes 33, or at least to provide only a few of them, since the aeration gas in zone 26 may pass at all times into zone 21 through the annular channel. I As stated hereinbefore, this invention is particularly suitable for handling powdered 'catalyst'. materials in connection with the catalytic treatment of petroleum products. One such catalyst material is known as Super Filtrol powder having a particle size between; 1 to 100 microns. A material of this type when allowed to stand for even a short period of time tends to bridge and lose its liquidlike properties. Centrifugal pumps .of conventional design are not capable of operating on such products.

pressuring gas in the regulation of While the invention has been described with y particular reference to the drawing. it should be understood from the foregoing that various modications are within the scope of the invention. For example, two pumps of the type shown in the drawing may be operated in that the receiving hopper Il of the first pump will become the feed hopper l I of the next pump, and so on. Catalysts are used inmany hydrocarbon conversion processes, and pumps, according to the presentv invention, will find application in any of such processes wherein a powdered catalyst is used. Examples of such conversion processes are catalytic cracking, hydroforming of naphtha,v

multiple stages so isomerizationof cracked naphthas,catalytic dehydrogenation of liquids and gases, pressure regeneration o`f contact materials, etc. It will also be `noted that whenever it is desired to use the pump in a catalytic conversion process, the feed hopper or low pressure zone and receivingho'pper or high pressure zone may be constituted Vby a portion of the apparatus already in use; for example, the receiving hopper may, in actual chamber in which the catalytic conversion of hydrocarbons takes place, and. likewise the feed hopper may be constituted by the chamber in which the regeneration of the catalyst takes place; or, as vanother example, the feed hopper may be` constituted by a cyclone separator.

A pump for powdered solid materials according to the present invention may be used for pumping catalyst against rline drop and pressure head froma reactor to a catalyst regenerator and- -from a regenerator to a reactor in a fluid catalys hydrocarbon conversion unit. Similarly it may be used, several stages if necessary, for introducing fresh or make-up catalyst into the system at any desired point such as the reactor or the regenerator. Another important application of my apparatus is a fluid conversion unit" for cir culating dense phase catalyst from a dense phase regenerator to a dense phase heat exchanger for cooling the catalyst and back to the dense phase regenerator. Other applications include transfer of powdered foods such as milk, sugar, cocoa, etc. from one zone to another, transfer of powdered minerals such'as Portland cement, whiting, contact clays, pottery clays and the like from one zone to another, etc.

practice, be the -for centrifuging it into the img an upper The scope of the present invention is to be defined by the claims appended hereto.

I claim:

1. A centrifugal pump for transferring an aerated, finely` divided solid material from a low pressure zone to a high pressure zone comprising rotatable means communicating with each of said zones for receiving the aerated finely divided solid material from the low pressure zone and and means for passing aeration gas countercurrently through the finely divided solid material while it is undergoing said centrifuging, whereby the finely divided solid material is maintained in an aerated condition during centrifugation. v, i

2. A centrifugal pump for finely dividedsolid material comprising a low pressure chamber, a high pressure chamber, rotatable means communicating with each of said chambers for receiving the nely divided solid material from the low pressure chamber and for centrifuging it into the high pressure chamber, and means for passing an aeration gas through the rotatable centrifuging means countercurrent to the flow of finely divided solid material whereby bridging and caking therein is prevented.

3. A centrifugal pump for finely divided solid material comprising a high pressure chamber, a

centrifuge rotatably mounted within said chamber, said centrifuge comprising two discs and a circular perforatedplate disposed therebetween and spaced therefrom, said discs and plate formzone through which the finely divided solid material passes and a lower zone, means for introducing an aeration gas into said lower zone, thejpressure in the vlower zone being greater than the pressure inthe high pressure chamber4 and the chamber-being greater than` the pressure in said upper zone, whereby the aeration gas will pass from the lower zone to y aerate the finely divided material countercurcentrifuged into the rently as it is centrifuged.

4. A centrifugal material comprising a low pressure chamber, a high pressure chamber, a rotatable neck member connecting said chambers, aicentrifuge connected to said rotatable neck member and disposed within said high pressure chamber, said centrifuge comprising two oppositely disposed substaritially conical discs and a circular perforated nla said finely divided solid material passing from the low pressure chamber through the rotatable neck member to one of said'zones where it is 4 high pressure chamber, means for introducing an aeration gas into the other of said zones, said aeration gas being under a pressure higher than the pressure in the high pressure chamber and in the first-mentioned zone, whereby jthe aeration gas will pass into said rst-mentioned zone countercurrently to the now of nnely divided solid material through said zone, thereby preventing caking and bridging of the finely divided solid material as it is centrifuged.

5. A centrifugal pump for finely divided solid material comprising a low pressure chamber, a high pressure-chamber, rotatable means mounted Within said high pressure chamber and cornmunicating with each of said chambers for receiving the finely divided solid material from the low pressure chamber and for centrifuglng it into the high -pressure chamber, and means for passing an aeration gas through the rotatable high pressure zone pressure in said high pressure the upper zone and there j pump for finely Adivided solid e disposed therebetween to form two zones,

centrifuging means -countercurrent to the flow of znely divided, solid material whereby bridging and caking therein is prevented.

6. A centrifugal pump material mentioned zone te the flow of nely divided, solid material whereby bridging and caking therein is prevented.

eountercurrent to the lmaterial whereby bridging and caking therein is prevented i MAURICE H. ARVESON. 

